/Engine/Plugins/EnhancedInput/Source/EnhancedInput/Public/UserSettings/EnhancedInputUserSettings.h
This will be called for each key profile when users initially call RegisterInputMappingContext, and on load during Serialize to correctly populate a loaded profile with all the known registered IMC's mappings.
virtual bool RegisterKeyMappingsToProfile ( [UEnhancedPlayerMappableKeyProfile](API\Plugins\EnhancedInput\UserSettings\UEnhancedPlayerMappableKeyProfil-) & Profile, const [UInputMappingContext](API\Plugins\EnhancedInput\UInputMappingContext) * IMC )